The Super Deluxe Edition includes three CDs, plus a Blu-ray that repeats the entire program, including the 2019 mix of the 1969 album found on CD One, in a variety of hi-res formats. That leaves two discs of sessions, basically 23 tracks in 90 minutes that chart the evolution of the band's last-recorded LP. (Let It Be was released later but recorded before Abbey Road.)

But like the earlier golden-anniversary boxes, the expanded Abbey Road is an essential chronicle of the final years of a group that changed the way pop music sounded, looked and was viewed by mainstream critics. It's their last masterpiece, and a work that, in a way, can be considered the culmination of their career.

It's also the Beatles' best-sounding album, so the 2019 mix of the original LP – by Giles Martin, who worked on the previous two sets – doesn't make any drastic changes to the songs you've known for all these years, unlike the Sgt. Pepper's remix that utilized the 1967 mono mix for a new stereo overhaul. The cornerstone of Abbey Road's anniversary edition is the sessions discs anyway, and they reveal some key elements about both the album and the group.

Notably, John Lennon, Paul McCartney, George Harrison and Ringo Starr are having a blast in the studio, a stark contrast to the Let It Be sessions that fell apart earlier in the year. Unlike the tension-filled dates from January 1969, the recordings that took place mostly that summer yielded a sense of lightness that had disappeared over the preceding years. The camaraderie the quartet wanted to get back to at the beginning of the year – following the divisive nature of the White Album – came to glorious fruition on Abbey Road.

The sessions actually start at the end of those earlier studio dates, with "I Want You (She's So Heavy)" featuring Billy Preston on organ. (He's on the finished version too but more pronounced here.) From there, the two discs work their way chronologically through the songs recorded from April though August, including a pair of songs that ended up on a single – "The Ballad of John and Yoko" and "Old Brown Shoe" – and McCartney solo demos for "Goodbye" and "Come and Get It," which he gave to Mary Hopkin and Badfinger, respectively.

Many of the songs came nearly fully formed to the studio, so there's not much variation between the original versions and the various alternate takes included here. Some of the earliest attempts turn out to be the most illuminating, like an early stab at "Oh! Darling," once again featuring a heightened Preston performance, and Harrison's two Abbey Road contributions – "Something" and "Here Comes the Sun" – without all the bells and whistles.

Listen to Take 4 of 'Oh! Darling'

But the centerpiece is "The Long One," the late-July title given to Side Two's still-breathtaking medley encompassing nine shorter songs (eight on the released album) penned by Lennon and McCartney. The sessions discs include individual versions of "You Never Give Me Your Money," "Polythene Pam," "Golden Slumbers" and the others, but it's this 16-minute "Trial Edit & Mix" that pulls it all together and gives Abbey Road its significance.

The pivotal point here is the inclusion of "Her Majesty," the 23-second acoustic McCartney ditty that ends the original album, between "Mean Mr. Mustard" and "Polythene Pam" in the medley's initial mix. Does it work better here? Hard to say after hearing it all these years in its place as the album's coda, but it sure doesn't sound out of place wedged between the two Lennon songs.

It also sheds new light on such a familiar work – as did the previous deluxe editions, which sparked re-evaluation of two classic albums.

If the Sgt. Pepper's anniversary edition pulled back the curtain on one of pop music's most heralded records and revealed all the gears that kept it moving, and the White Album set signaled a new beginning rather than the beginning of the end that's so often read into the work, then this new Abbey Road makes a strong case for its place at the very top of all-time-best-Beatles-albums lists.

Five decades on, it sounds that great and maybe even better than you remember. The sessions show just how strong the band still was as a performing unit, even after retiring from live appearances three years earlier. There isn't a note out of place; many of the various takes could have been released without altering the album's place in history.

Abbey Road's legacy is that of a band going out on top. (The four Beatles were in the studio together for the last time during the final days of the sessions to mix and sequence the LP.) Hearing them on this excellent box reinforces what we've all heard so many times before: There'll never be another band like them.